A sharp increase in air traffic in recent years has led to a high utilization and partially an overloading of the air traffic capacity of many airports. Without expanding the physical runway facilities and the like of existing airports, or building new airports, a further increase in capacity can only be achieved by reducing the time required for the take-off and landing of each aircraft. Reducing the time required for the take-off of an aircraft basically requires an increase in the power of the aircraft, and is thus complicated and costly. Reducing the overall time required for the landing of an aircraft must consider that the landing process includes several phases, for example the gliding approach and descent along a glide path, flaring from the glide path to an essentially level final landing path, and finally floating or settling out to the touch down point, and then rolling out and braking along the runway. This landing process is initiated already at a considerable distance and time out from the destination airport, by a controlled descent on the so-called glide path or glide slope. Since the gliding descent along the glide path takes up a substantial amount of the total time of the overall landing process, reducing the time required for this gliding descent will have a substantial impact on shortening the overall time required for the landing process, thereby reducing the total landing and take-off cycle time, and increasing the landing capacity per hour of the airport.
The descent of the aircraft along the glide path or glide slope is controlled by the relationship of lift and drag of the aircraft. In this context, the coefficient of lift of the aircraft is dependent on the angle of attack or incidence of the aircraft as well as the incident flow velocity of the relative wind with respect to the aircraft. Modern conventional aircraft use their typical control surfaces or control elements, such as flaps, rudder, spoilers, etc. and adjustments of the propulsion engine thrust, to control the descent of the aircraft along the glide path. Unfortunately, these conventional control elements can only achieve a variation of the lift and of the aerodynamic drag in a mutually coupled manner. In other words, any adjustment of the conventional control elements will simultaneously influence both the total lift and the total drag of the aircraft. This means that an intended change of the glide path slope for a given angle of attack of the aircraft by means of a drag variation (e.g. by extending the flaps or deflecting the spoilers) will simultaneously cause a change of the lift. The resulting compound effects of any control adjustment are thus rather complex, and consequently require rather complex systems for controlling the adjustments of the control elements, and substantially limit the possibility of any further reductions in the time or distance required for the landing approach of the aircraft.